/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
using System;
using java = biz.ritter.javapi;

using org.apache.commons.codec;

namespace org.apache.commons.codec.language
{

    /**
     * Utility methods for {@link Soundex} and {@link RefinedSoundex} classes.
     * 
     * @author Apache Software Foundation
     * @version $Id: SoundexUtils.java 658834 2008-05-21 19:57:51Z niallp $
     * @since 1.3
     */
    sealed class SoundexUtils
    {

        /**
         * Cleans up the input string before Soundex processing by only returning
         * upper case letters.
         * 
         * @param str
         *                  The String to clean.
         * @return A clean String.
         */
        internal static String clean(String str)
        {
            if (str == null || str.length() == 0)
            {
                return str;
            }
            int len = str.length();
            char[] chars = new char[len];
            int count = 0;
            for (int i = 0; i < len; i++)
            {
                if (java.lang.Character.isLetter(str.charAt(i)))
                {
                    chars[count++] = str.charAt(i);
                }
            }
            if (count == len)
            {
                return str.toUpperCase(java.util.Locale.ENGLISH);
            }
            return new String(chars, 0, count).toUpperCase(java.util.Locale.ENGLISH);
        }

        /**
         * Encodes the Strings and returns the number of characters in the two
         * encoded Strings that are the same.
         * <ul>
         * <li>For Soundex, this return value ranges from 0 through 4: 0 indicates
         * little or no similarity, and 4 indicates strong similarity or identical
         * values.</li>
         * <li>For refined Soundex, the return value can be greater than 4.</li>
         * </ul>
         * 
         * @param encoder
         *                  The encoder to use to encode the Strings.
         * @param s1
         *                  A String that will be encoded and compared.
         * @param s2
         *                  A String that will be encoded and compared.
         * @return The number of characters in the two Soundex encoded Strings that
         *             are the same.
         * 
         * @see #differenceEncoded(String,String)
         * @see <a href="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/tsqlref/ts_de-dz_8co5.asp">
         *          MS T-SQL DIFFERENCE</a>
         * 
         * @throws EncoderException
         *                  if an error occurs encoding one of the strings
         */
        internal static int difference(StringEncoder encoder, String s1, String s2)
        {// throws EncoderException {
            return differenceEncoded(encoder.encode(s1), encoder.encode(s2));
        }

        /**
         * Returns the number of characters in the two Soundex encoded Strings that
         * are the same.
         * <ul>
         * <li>For Soundex, this return value ranges from 0 through 4: 0 indicates
         * little or no similarity, and 4 indicates strong similarity or identical
         * values.</li>
         * <li>For refined Soundex, the return value can be greater than 4.</li>
         * </ul>
         * 
         * @param es1
         *                  An encoded String.
         * @param es2
         *                  An encoded String.
         * @return The number of characters in the two Soundex encoded Strings that
         *             are the same.
         * 
         * @see <a href="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/tsqlref/ts_de-dz_8co5.asp">
         *          MS T-SQL DIFFERENCE</a>
         */
        static int differenceEncoded(String es1, String es2)
        {

            if (es1 == null || es2 == null)
            {
                return 0;
            }
            int lengthToMatch = java.lang.Math.min(es1.length(), es2.length());
            int diff = 0;
            for (int i = 0; i < lengthToMatch; i++)
            {
                if (es1.charAt(i) == es2.charAt(i))
                {
                    diff++;
                }
            }
            return diff;
        }

    }
}